Numerous water spray systems have been developed for producing snow wherein water and air under pressure are in some manner mixed and commingled. The principle involved is to reduce the size of water particles to the smallest size possible, typically by high pressure discharge of water through an atomizing nozzle orifice to form a spray, and augmented by injection of compressed air directly or indirectly with the water spray or mixing with air within a mixing chamber, to thereby form seed crystals.
Spray-made snow is formed from seed crystals. Preferably, these seed crystals are formed from the expansion of compressed air expelled into the atmosphere within and around which minute water particles freeze and form spray-made snow. The compressed air is at a higher temperature than normal ambient winter air conditions and when expelled to ambient will expand to atmospheric pressure while simultaneously dropping greatly in temperature. Because of the refrigerating effect of such pressure reduction, if there is a high quantitative level of moisture vapor present in the compressed air, such moisture vapor upon expansion will condense and freeze, immediately forming seed crystals necessary for seeding atomized water spray particles for snow making. Of course, impingement of the expanding compressed air stream upon associated atomizing-spray-generated water particles also forms such seed crystals. These seed crystals are immediately formed because of the extremely low temperature condition obtained through the expansion of the air together with the freezing effect of atmospheric conditions of winter, that is, wet bulb temperatures below 32° F. The seed crystals thus formed can be combined with the remaining water particles of the atomized water spray in a manner to form more spray-made snow.
In connection with the atomizing of water for snow making it has long been known that the water particle size should be as small as possible, in many cases as small as 200 microns or less, because if such particles are too large, depending on ambient weather conditions and the ratio of water to air mixture, they will produce ice or sleet particles which are unsatisfactory for desirable skiing conditions. Also, the greater the water pressure at the discharge nozzle, the smaller the water particles or moisture droplets upon nozzle discharge. However, the water particles should not be so small that they drift away, evaporate and/or sublimate.
Further, information and history of various methods and apparatus for spray-making snow are set forth in columns 1 through 8 of the Kircher et al. U.S. Pat. No. 6,161,769, and in the references cited therein, all of which are incorporated herein by reference for brevity.
More recent examples of United States patents directed to spray snow making pipe towers are as follows (also all incorporated “herein” by reference for brevity): McKinney U.S. Pat. No. 5,810,251; Dupre U.S. Pat. No. 5,908,156; McKinney U.S. Pat. No. 5,979,785; Pergay et al. U.S. Pat. No. 6,508,412; Dupre U.S. Pat. No. 6,543,699 and Jervas U.S. Pat. No. 6,547,157.